Are interior points also limit points

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SUMMARY

Interior points are not included in limit points, but they are related concepts in topology. An interior point of a set S requires that an open ball around it is entirely contained within S, while a limit point only requires the existence of another point in the open ball that is not the center point. The closure of a set S is defined as the union of its interior points and its boundary points, confirming that limit points are part of this closure. Therefore, while all interior points are limit points, not all limit points are interior points.

PREREQUISITES
  • Understanding of basic topology concepts, including open and closed sets.
  • Familiarity with the definitions of interior points and limit points.
  • Knowledge of the concept of closure in a topological space.
  • Ability to work with open balls in metric spaces.
NEXT STEPS
  • Study the properties of open and closed sets in topology.
  • Learn about the concept of closure and its implications in metric spaces.
  • Explore examples of limit points and interior points in various topological spaces.
  • Investigate the relationship between limit points, interior points, and boundary points in detail.
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Students and professionals in mathematics, particularly those studying topology, as well as educators looking to clarify concepts related to limit points and interior points.

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Homework Statement


Are interior points included in (or part of) limit points?

Homework Equations


Since the definition of interior points says that you can find a ball completely contained in the set. For limit points, it's less strict, you just have to find a point other than the center.

The Attempt at a Solution


My guess is yes, but I've never read it anywhere in the book.
 
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You should double check on that but I think the set of all limit points of S is called the closure of S, which is the union of the interior of S and the boundary of S, so the short answer would be: YES
 
susskind_leon said:
You should double check on that but I think the set of all limit points of S is called the closure of S, which is the union of the interior of S and the boundary of S, so the short answer would be: YES

We use open ball to define both limit point and interior point.

Say, we have some set of space, call it S.

When point p is a limit point of S, we say that we can find a point q (q≠p) in B(x, r), meaning an open ball centered at x, with radius r.

When it is interior point, we say all of the points in this ball is also in S.

So, for limit point, you just need one other point. For interior point, you need all points in the ball is also contained in set S.
 

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